The present invention relates to a method for the remediation of contaminated soils of anthropogenic or geologic origin in which, without transport of the soil to the soil surface, a loosening of the soil structure is achieved by injecting a liquid under high pressure progressively into at least one cylindrically shaped soil body.
Furthermore, the present invention relates to an apparatus for a soil remediation process consisting of a drill pipe (drill poles) with a drill head and an inlet conduit. Above the drill head there is at least one outlet nozzle for the liquid being ejected under high pressure.
Methods for the remediation of contaminated soils have been known, in which the contaminants are washed off the soil particles by a jet of water or a remediation medium injected into the soil under high pressure. The resulting mixture of remediation medium, contaminants and soil particles is then transported to the soil surface where the remediation medium or the water are recycled in a treatment plant. The separated contaminants are then stored in a suitable landfill, if necessary. With these known methods it is inevitable that soil particles are transported to the soil surface together with the contaminants carrying remediation medium, therefore the particles removed from the soil, e.g., silt, sand, have to be returned to the soil after complete decontamination in the treatment plant or substituted by suitable additives.
Furthermore, on-site soil remediation methods (in situ) are known, which employ microbiological decomposition of certain contaminant groups by using a directed introduction of nutrients into the soil from the soil surface or a specially designed introduction well to thereby stimulate a higher metabolic rate in the soil microorganisms naturally present. In one embodiment of this known method, in addition to the nutrients, the microorganisms chosen for the treatment are also introduced into the soil.
The structure of a naturally formed soil is heterogeneous and anisotropic. The transition between different soil layers is usually abrupt and intermittent. Differences of the soil layers in permeability, in anisotropic properties as well as in affinity and adsorption tendencies towards a contaminant or its aqueous solution or suspension often impede the realization of microbiological insitu processes or result in failure. Usually soil layers with the lowest permeability are especially contaminated. When soil layers of different permeability are present, introduced substances and microorganisms in aqueous solution tend to move and remain in soil layers that are highly permeable and in which contamination is usually low. Nearly impermeable soil layers may limit the success of microbiological in-situ processes or completely prevent contaminants and microorganisms from coming into contact.
It is therefore an object of the present invention to provide a method for the remediation of contaminated soils, in which the removal or conversion of the contaminants is not carried out at the soil surface but in the soil (in-situ) without providing an encapsulation from the surrounding soil. Furthermore, a suitable apparatus for the realization of the method is provided.